Expert Testimony in the Dock
| Author | Adam Wilson |
| DOI | 10.1350/jcla.2005.69.4.330 |
| Published date | 01 August 2005 |
| Date | 01 August 2005 |
| Subject Matter | Article |
Expert Testimony in the Dock
Adam Wilson*
Abstract This article focuses predominantly on the recent miscarriages of
justice in the cases of Angela Cannings and Sally Clark. The article
identifies possible causes of error in trials involving expert testimony. It is
suggested that admission of scientific evidence may inevitably elicit such
miscarriages of justice. In order to reduce their frequency, however,
experts need training in both scientific and forensic methodology. The
science community must also ensure vigilance against scientific dogma.
The cases show that responsibility does not lie solely at the feet of expert
witnesses. Advocates need training in how to deal with expert testimony.
Finally, the use of the jury in complex scientific trials is considered and
approved.
Expert testimony has recently been criticised following the recent well-
publicised cases of Sally Clark and Angela Cannings. Following the
judgment in Cannings1the Attorney-General instigated an urgent review
of convictions involving the murder, manslaughter or infanticide of an
infant aged below two years of age, within the last 10 years. As of 4
March 2004 some 288 cases had been identified, with 86 defendants still
in custody.2The Law Society responded promptly issuing advice in
relation to both criminal and family cases. The Society suggested that
practitioners may wish to advise clients, or former clients, to seek review
proactively notwithstanding the fact that few would fall within the
remit of the judgment.3The potential repercussion of these cases, in
terms of number of reviews or successful appeals, may be substantial.
The extent of human suffering is incalculable.
The initial press response was unequivocal. Failure of forensic testi-
mony was attributed to individual, formerly eminent, experts. This
article suggests that, whilst scientists did err, it is too simplistic to lay
blame solely at the feet of individual experts. If the salient objective is to
minimise recurrence of such miscarriages of justice, then personal vili-
fication is a poor substitute for reasoned analysis. Vilification detracts
from identifying the wider causes of miscarriages of justice in the
context of expert testimony.
This article reviews the cases of Sally Clark and Angela Cannings to
identify how error may arise in cases which centre on expert opinion
evidence. Brief reference is also made to the experience from the Trupti
Patel trial and cases focusing on Munchausen’s Syndrome by Proxy.
Though these cases all focus on instances of alleged murder of a baby, it
* Senior Lecturer in Law, Sheffield Hallam University; e-mail A.J.Wilson@shu.ac.uk.
1R v Cannings [2004] EWCA Crim 1, [2004] 2 Cr App R 7.
2 Letter dated 4 March 2004 from the Legal Secretariat to the Law Officers to Peter
Williamson (it must be remembered these may well be appropriate convictions).
3 Letter dated March 2004 from Peter J. Williamson, President of the Law Society.
330
is hoped that the lessons learnt from them inform all trials involving
expert opinion evidence.4
The analysis begins below by identifying numerous ways in which
expert testimony may fall into error. Initially, possible errors on the part
of individual experts are highlighted. The net is then cast somewhat
wider to identify problems inherent in forensic science. The proposition
is put forward that admission of a genus of evidence with innate flaws
firmly places miscarriages of justice in a wider social context.
Having examined scientific error the perspective shifts towards a
critical evaluation of advocacy skills. It is suggested that the recent
miscarriages of justice were attributable, in part, to less than vigilant
advocacy. The issue of training and quality of advocates is duly
considered.
Finally, there is a brief discussion as to whether the jury system is best
suited to cases involving expert testimony.
Errors attributable to individual experts
Individual experts may make errors in a number of different ways. First,
their scientific methodology may fall below par. Secondly, they may
neglect or be ignorant of principles of forensic investigation. Finally,
they may proffer inconsistent opinions. These are considered in turn
below.
Poor scientific methodology
The first source of error is attributable to poor scientific methodology.
The Clark case5is, regrettably, illustrative. Dr Williams, a prosecution
pathologist, had relied, in part, on evidence of haemorrhages in the eyes
and eyelids to justify an opinion that Harry had been murdered.6Pro-
fessor Luthert, a specialist eye pathologist, clarified that in respect of
intra-retinal haemorrhaging the bleeding revealed was of post-mortem
origin attributable to an error of slide preparation.7Professor Luthert’s
assertions were persuasive enough for a highly eminent prosecution
witness, Professor Green, to amend his views.8In addition, Professor
Luthert thought that haemorrhages on the surface of the eye may have
been attributable to blood dripping onto them during dissection.9
Errors in slide preparation, or the possibility of allowing blood to drip,
are a fundamental scientific error. It is obviously essential to ensure
vigilance when tests or experiments are undertaken. This point is accen-
tuated as further experts may be reliant upon the accuracy of the test to
4 It is a peculiarity that the cases only attracted a murder charge as the defendants
pleaded not guilty. Had the parties pleaded guilty, the charge of infanticide may
have been pursued. The likely sentence in such instances would have been a
community sentence. The sentence for murder is a mandatory life sentence.
5R v Clark (Sally) (No. 2) [2003] EWCA Crim 1020, [2003] 2 FCR 447.
6 Ibid. at [69].
7 Ibid. at [70].
8 Ibid.
9 Ibid. at [71]. This belief was not necessarily accepted and cannot be taken as
conclusively showing poor scientific methodology.
Expert Testimony in the Dock
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